An investigation team led by Colorado School of Public Health researchers looked at the relationship between marijuana consumption, respiratory function and symptoms in a study involving 2,300 people between the ages of 40 – 80, many of which are also tobacco users, NORML reports.

The authors said, “Neither current nor former marijuana use was associated with increased risk of cough, wheeze, or chronic bronchitis when compared to never marijuana users after adjusting for covariates. … Current and former marijuana smokers had significantly higher FEV1 (forced expiratory volume) … when compared to never users. … Both current and former marijuana use was associated with significantly less quantitative emphysema … when compared to never users, even after adjusting for age, … current tobacco smoking pack years, and BMI. … In agreement with other published studies, we also did not find that marijuana use was associated with more obstructive lung disease.”

Combined long-term use of tobacco and marijuana isn’t related to additive, adverse effects on the lungs.

The study authors concluded that, “Among older adults with a history of tobacco use, marijuana use does not appear to increase risk for adverse lung function. … There may be no to little increased risk of marijuana use for a further increase in respiratory symptoms or adverse effects on lung function among those with a history of concomitant tobacco use.”